diff --git a/packages/opencode/src/acp/service.ts b/packages/opencode/src/acp/service.ts
index 36e8375f5cc4..0ebe79ca7a1c 100644
--- a/packages/opencode/src/acp/service.ts
+++ b/packages/opencode/src/acp/service.ts
@@ -243,9 +243,12 @@ export function make(input: {
   const listSessions = Effect.fn("ACP.listSessions")(function* (params: ListSessionsRequest) {
     const cursor = params.cursor ? Number(params.cursor) : undefined
     const limit = 100
+    // Route through the cross-project session listing so an omitted cwd
+    // returns every known session, per the ACP session/list spec, instead of
+    // being scoped to the ACP process's own project.
     const sessions = yield* request(
       () =>
-        input.sdk.session.list(
+        input.sdk.experimental.session.list(
           {
             ...(params.cwd ? { directory: params.cwd } : {}),
             roots: true,
diff --git a/packages/opencode/test/acp/service-session.test.ts b/packages/opencode/test/acp/service-session.test.ts
index 890719072abf..acd28a6e24e2 100644
--- a/packages/opencode/test/acp/service-session.test.ts
+++ b/packages/opencode/test/acp/service-session.test.ts
@@ -160,6 +160,10 @@ describe("ACP service sessions", () => {
       title: `Session ${index + 1}`,
       time: { created: index + 1, updated: index + 1 },
     }))
+    const list = (input: { directory?: string }) =>
+      Promise.resolve({
+        data: input.directory ? sessions.filter((session) => session.directory === input.directory) : sessions,
+      })
     const sdk = {
       config: {
         providers: () => Promise.resolve({ data: { providers: [provider], default: { test: modelID } } }),
@@ -188,10 +192,7 @@ describe("ACP service sessions", () => {
       session: {
         create: () => Promise.resolve({ data: { id: "ses_new" } }),
         get: () => Promise.resolve({ data: { id: "ses_loaded" } }),
-        list: (input: { directory?: string }) =>
-          Promise.resolve({
-            data: input.directory ? sessions.filter((session) => session.directory === input.directory) : sessions,
-          }),
+        list,
         messages: () => Promise.resolve({ data: messages }),
         prompt: (input: unknown) => {
           prompts.push(input)
@@ -234,6 +235,11 @@ describe("ACP service sessions", () => {
           return Promise.resolve({ data: { id: `fork_${input.sessionID}` } })
         },
       },
+      experimental: {
+        session: {
+          list,
+        },
+      },
       mcp: {
         add: (input: { name?: string }) => {
           if (input.name) mcpAdds.push(input.name)